It is known that many materials, such as carbon/carbon composites, carbon fibers, graphite, and certain metals, have properties which make them attractive for use in aerospace and other applications in which their susceptibility to oxidative deterioration at elevated temperatures is a serious disadvantage. Such materials, as well as other materials like alumina, silica, lithia, mullite, etc., can also be damaged by heat, abrasion, or corrosion. It would be desirable to find a means of protecting those materials, and it has been proposed to provide such protection with ceramic coatings. However, known ceramic coatings have proved to be inadequate.
As disclosed in U.S. Pat. No. 4,705,837 (Seyferth et al.) and European Patent Application No. 237,199 (Funayama et al.), it is known that ceramics can be obtained from polysiloxazanes. U.S. Pat. No. 4,482,689 (Haluska) discloses boron-containing metallosilazane polymers which are also useful in forming ceramic materials.